The present invention relates to fiber-reinforced polymer compositions comprising polyamide resins and polyolefins as main components, and more particularly to fiber-reinforced polymer compositions comprising polyamide resins and polyolefins as main components, which are excellent not only in thermal deformation resistance, chemical resistance and impact resistance, but also in antifreeze resistance and moldability, and further have remarkably improved Geer oven life and copper-contacted Geer oven life.
Containers such as radiator tanks of automobiles have been getting increasingly produced from plastics, for the purpose of reducing their weight. As plastic materials for producing such containers, polyamide resins are highly suitable because they are light and excellent in impact resistance, heat resistance, chemical resistance, etc. Particularly, nylon 6 and nylon 66 having excellent strength and heat resistance and blended with glass fibers are widely used.
However, despite the fact that polyamide resins reinforced with glass fibers, etc. are excellent in heat resistance, mechanical strength and long-term durability, they are generally poor in water resistance, moldability, chemical resistance and antifreeze resistance. Particularly, the antifreeze resistance is an important characteristic when they are used for radiator tanks of automobiles, because they are exposed to an antifreeze for a long period of time.
The above desired properties, which are insufficient in the polyamide resins, are generally owned by polyolefins. Thus, various compositions based on polyamide resins, polyolefins and glass fibers have been proposed.
Japanese Patent Publication No. 61-26939 discloses radiator tanks made of compositions comprising (a) polyamide resins, (b) modified polymers obtained by grafting ethylenically unsaturated carboxylic acids or their anhydrides to polypropylene resins, and (c) fibrous reinforcing materials, a weight ratio of the component (a) to the component (b) being 70:30-95:5, and the component (c) being 40-200 parts by weight per 100 parts by weight of the total amount of the component (a) and the component (b).
Japanese Patent Laid-Open No. 61-76540 discloses molded plastic articles for automobiles having one surface exposed to the atmosphere and the other surface exposed to water and being repeatedly subjected to high temperature, the molded articles being made of (A) 90-10 parts by weight of olefin polymers, (B) 10-90 parts by weight of polyamides, and (C) 0.1-20 parts by weight, per 100 parts by weight of (A)+(B), of modified olefin polymers grafted with 0.05-10 parts by weight of monomers selected from unsaturated carboxylic acids or their derivatives.
Japanese Patent Laid-Open No. 62-241940 discloses plastic compositions for radiator tanks for automobiles comprising (A) 30-95 weight % of olefin polymers, (B) 5-70 weight % of polyamides, and (C) 5-200 parts by weight, per 100 parts by weight of (A)+(B), of glass fibers impregnated with acrylic resins as tying agents.
However, despite the fact that in the conventional compositions, the compatibility of polyamide resins and polyolefins and the adhesion of glass fibers to the matrix resins are improved to some extent, they are still insufficient for severe conditions required for radiator tanks, etc.
Further, the conventional polyamide resin/polyolefin compositions are extremely vulnerable to deterioration when being in contact with copper at a high temperature for a long period of time.